CN120399966A

CN120399966A - Cross-feeding composite bacterial agent for simultaneous removal of mineral processing reagents and heavy metal pollution and its application

Info

Publication number: CN120399966A
Application number: CN202510585408.8A
Authority: CN
Inventors: 李泽敏; 晏波; 陈涛; 周嘉仪; 孙佳成; 涂姝臣
Original assignee: South China Normal University
Current assignee: South China Normal University
Priority date: 2025-05-08
Filing date: 2025-05-08
Publication date: 2025-08-01
Anticipated expiration: 2045-05-08
Also published as: CN120399966B

Abstract

The present invention's "cross-feeding composite inoculant for simultaneous removal of mineral processing agents and heavy metal contamination and its application" belongs to environmental microbial remediation and wastewater treatment technologies. The inoculant is prepared by inoculating a mixture of a suspension of sulfur-oxidizing bacteria (Thiobacillus sp ) and a suspension of sulfate-reducing bacteria ( Desulfotomaculum profundi ) into a liquid culture medium. The mixture is cultured at a constant temperature of 30°C and microaerobic conditions, with shaking at 120 rpm, until the OD600 value reaches 0.6-1.0. The cross-feeding composite inoculant achieves simultaneous efficient xanthate degradation and heavy metal immobilization (e.g., Cu²⁺, Pb²⁺ , and Zn²⁺) in a single reactor through the metabolic synergy of sulfur-oxidizing bacteria (Thiobacillus sp) and sulfate-reducing bacteria (Desulfotomaculum profundi).

Description

Cross feeding composite microbial inoculum for synchronously removing mineral separation agent and heavy metal pollution and application thereof

Technical Field

The invention belongs to the technology of environmental microorganism restoration and wastewater treatment, and particularly relates to a cross-feeding composite microbial agent for synchronously removing mineral dressing agents and heavy metal pollution and application thereof.

Background

Lead-zinc tailings in China are commonly and severely polluted by As, cd, cu, cr, pb, zn and other heavy metals. In particular, the presence of Cd as a metallic element closely related to Zn and having significant toxicity in lead-zinc tailings has attracted a great deal of attention. Studies have shown that lead-zinc tailings in guangdong province are particularly prominent in Pb and Zn concentrations, while As concentrations in guangdong province and in hunan province are high, and Cd pollution in guangdong province and in gansu province is particularly serious. In addition, the highest concentration of Cr in lead-zinc tailings of Guizhou province. The problem of heavy metal contamination of lead zinc tailings is serious, and even after the tailings pond is closed, the lead zinc tailings can continue to be a source of contamination for decades or even centuries. The environmental hazard mainly comes from the fact that the Pb and Zn contents are too high, so that the heavy metal pollution index is still continuously increased after the tailings are discarded. In the long-term open-air stockpiling process of tailings, heavy metal pollution is caused to the soil around the tailings pond by the actions of sand dust blowing, rainfall runoff, dam break dumping and the like. Heavy metal pollution such as As, cd, cu, cr, pb, zn with different degrees exists in the soil around the lead-zinc mine tailing pond in China.

In addition, in the modern mineral separation process, the addition of chemical mineral separation agents is a core link for realizing effective separation of minerals. These agents are diverse and include inorganic compounds, organic chemicals and various types of polymeric substances. In particular, in the beneficiation of lead zinc ores, more than 47 different beneficiation reagents have been widely used at present. Wherein, the use amount of the organic mineral separation agent xanthate in the flotation process is close to the use level of pesticides in the agricultural field. These agents contain a variety of potentially toxic organic compounds such as alkyl xanthates, nigrosine drugs, etc., which have been recognized as typical environmental pollutants. The world-wide use of organic flotation agents is reported to be comparable to pesticides, with a total usage of 400 tens of thousands of tons per year. Taking xanthates as an example, worldwide usage in 1980 was about 52000 t, and 2025 would be expected to reach 371826 t. In the mineral separation production process, about 70% -90% of the organic mineral separation agents are adsorbed on the surfaces of the tailing particles or remain in water and are discharged into a tailing pond together with the tailing and the mineral separation wastewater to form an organic pollution source. Meanwhile, under the actions of long-term natural oxidation, rainwater leaching, microorganisms and the like, the tailings in the tailing pond are easy to release associated heavy metal ions such As Pb, cd, as and the like, so that heavy metal pollution is formed. In addition, the xanthate and the decomposition products thereof can be subjected to adsorption complexing action with heavy metals to form complex xanthate-heavy metal combined pollution, and the process is likely to increase the dissolubility of the heavy metals, change the mobility and bioavailability of the heavy metals and cause more serious ecological environmental hazard.

However, the prior art has certain limitations, such as that the chemical oxidation method adopts Fenton reagent (Fe ²⁺/H₂O₂) to degrade xanthate, the medicament cost is up to 80-120 yuan/ton, halogenated byproducts (such as chloroform, the concentration is more than 50 mug/L) are generated, and the limit value of the quality standard of the surface water environment (GB 3838-2002) is exceeded. Meanwhile, the synchronous removal of xanthate and heavy metals cannot be realized by a single strain biological method. In addition, a step-by-step process (CN 105800796A) of biodegradation and chemical precipitation is adopted, the treatment process is complex, the investment cost is high, and the re-dissolution rate of heavy metals under the acidic condition is more than 30%.

Solves the problems of low xanthate-heavy metal composite pollution treatment efficiency, high cost, large secondary pollution risk, poor flora stability and the like in the prior art, and has important theoretical and practical significance for treating composite pollution tails caused by nonferrous metal mines.

Disclosure of Invention

Based on the requirements or problems in the field, the invention provides a composite microbial agent for synchronously removing non-ferrous metal mine beneficiation reagent-heavy metal composite pollutants, in particular to a bioremediation method for synchronously degrading xanthate and synchronously fixing heavy metals (such as copper, cadmium, lead and zinc) in a reactor through the metabolic synergistic effect of thiobacillus sp and Desulfotomaculum profundi. The method has the advantages of wide pollutant concentration application range, simple process flow, convenient operation, lower cost and no secondary pollution, high removal efficiency of the combined pollution of the beneficiation reagent and the heavy metal, stable effluent quality and obvious advantages in practical application, and is suitable for treating organic sulfide-heavy metal combined pollutants in mine wastewater, electroplating wastewater and chemical wastewater.

The specific technical scheme is as follows:

The invention provides a cross-feeding composite microbial inoculum for synchronously removing mineral separation agents and heavy metal pollution, which is characterized in that mixed bacterial liquid of a sulfur oxidizing bacteria (thiobacillus sp) bacterial suspension and a sulfate reducing bacteria (Desulfotomaculum-profundi) bacterial suspension is inoculated into a liquid culture medium, and 120 rpm is subjected to shaking culture under the conditions of constant temperature and micro oxygen at 30 ℃ until an OD600 value reaches 0.6-1.0 to obtain the cross-feeding composite microbial inoculum;

The liquid culture medium is a basic inorganic salt culture medium containing simulated composite pollutants, and has the formula of 0.1 g/L NH ₄Cl、0.05 g/L CaCl₂、0.2 g/L MgSO₄, 100 mg/L xanthate, 50mg/L cadmium chloride and pH of 7.0;

During inoculation, the volume ratio of the mixed bacterial liquid to the liquid culture medium is 1:50, and the concentration ratio of the sulfur oxidizing bacteria to the sulfate reducing bacteria in the mixed bacterial liquid is 1:3-3:1;

The cross feeding means that sulfur groups in xanthate are oxidized into SO ₄ ^2- by sulfur oxidizing bacteria in the composite microbial inoculum, and electron acceptors required by sulfate reducing bacteria are provided, meanwhile, the sulfate reducing bacteria take sulfur oxidizing bacteria degradation intermediate products as carbon sources, SO ₄ ^2- is reduced to generate S ^2-, and the produced S ^2- and heavy metals form stable sulfide precipitates.

Preferably, the concentration ratio of the sulfur oxidizing bacteria suspension to the sulfate reducing bacteria suspension in the mixed bacterial liquid is 1:1-1:2, the micro-aerobic condition means that dissolved oxygen is maintained at 0.3-0.5 mg/L through intermittent micro-aeration regulation and control, and the xanthate means potassium butylxanthate.

Preferably, the cross-fed complex microbial inoculum is characterized in that the sulfur oxidizing bacteria are the bacterial species with deposit number DSM 612 and the sulfate reducing bacteria are the bacterial species with deposit number DSM 24093.

In another aspect of the invention, a method for synchronously removing nonferrous metal mine beneficiation reagent and heavy metal pollution is provided, which is characterized in that:

feeding, namely feeding the cross feeding composite microbial inoculum according to any one of claims 1-3 into waste water to be treated containing nonferrous metal mine beneficiation reagent and heavy metal pollution for reaction, wherein the feeding volume is 5-15% of the volume of a reaction container;

The reaction condition is that the water inlet and the water outlet of a reaction container are controlled at the temperature of 10-30 ℃ to ensure that the hydraulic retention time of the sewage to be treated is 2-10 hours, and a carbon source is not required to be added in the process;

The mineral separation agent is xanthate, and the heavy metal is at least one of copper, cadmium, lead and zinc.

Preferably, the method is characterized in that the pH value of the wastewater to be treated is 7.0-8.5, the concentration of xanthate is 1.0-1000 mg/L, and the concentration of heavy metal elements is 0.1-100.0 mg/L.

Preferably, the method is characterized in that the reaction condition further comprises controlling the concentration of dissolved oxygen to be less than or equal to 0.5 mg/L.

The method is characterized in that the reaction container is an up-flow packed bed reactor, water inflow is waste water to be treated containing nonferrous metal mine beneficiation reagent and heavy metal pollution, and the reaction container is filled with a microbial inoculum carrier, wherein the ratio of the microbial inoculum carrier volume to the reactor volume is 30-45%;

After the cross feeding composite microbial inoculum is added, standing for 1-2 hours to enable the microbial inoculum to be adsorbed to the microbial inoculum carrier;

The microbial inoculum carrier is biochar-nano ferroferric oxide.

Preferably, in the method, the hydraulic retention time is controlled and controlled to be 8 hours during operation, the temperature is 35+/-1 ℃, the oxidation-reduction potential (ORP) is-150+/-10 mV, the Dissolved Oxygen (DO) is maintained to be 0.5-1.0 mg/L in an aerobic zone, the anaerobic zone is lower than 0.2 mg/L, and the flow rate is controlled to be 6.25L/h through a peristaltic pump to realize continuous water inlet and outlet.

Preferably, the method further comprises solid-liquid separation of the treated wastewater, wherein the supernatant is clean water for removing xanthate-heavy metal combined pollution, the solid is sulfide precipitate, and the heavy metal resource is recovered through magnetic separation.

The conception and beneficial effects of the invention

The invention constructs a cross feeding composite microbial inoculum consisting of Sulfur Oxidizing Bacteria (SOB) -Sulfate Reducing Bacteria (SRB) for synchronously removing xanthate-heavy metal composite pollution. The method is characterized in that sulfur groups in xanthate of beneficiation reagent are oxidized into SO ₄ ^2- by SOB through a cross feeding metabolic pathway, toxicity is reduced, an electron acceptor required by SRB is provided, SOB degradation intermediate products (formic acid, acetic acid, methanol and other small molecular organic matters) are used as carbon sources of SRB by the SRB through a cross feeding mechanism, SO ₄ ^2- is reduced to generate S ^2- and heavy metals to form stable sulfide precipitate, after solid-liquid separation of the precipitate, supernatant fluid is standard-reaching wastewater for removing xanthate-heavy metal composite pollution, and the generated sulfide precipitate is subjected to magnetic separation to recover heavy metal resources to realize heavy metal recovery.

Experimental data shows that the Sulfur Oxidizing Bacteria (SOB) -Sulfate Reducing Bacteria (SRB) composite microbial inoculum system constructed by the invention can realize high-efficiency synchronous treatment of xanthate-heavy metal composite pollution without adding additional carbon source in the treatment process, and has remarkable environmental benefit, economic benefit and technical advantage. The composite microbial inoculum drives sulfur circulation through a micromolecular organic matter/SO ₄ 2-cross feeding metabolic network, SO that the generated S2-fixed heavy metal (the removal rate is more than or equal to 99.8%) is utilized while xanthate is efficiently degraded (the degradation rate is more than or equal to 99 percent), the treatment efficiency is improved by 1.8 times compared with a single strain process, and a chemical oxidant is not needed. The process thoroughly avoids secondary pollutants such as bromate, chlorinated byproducts and the like generated by a chemical method, the xanthate is completely mineralized into CO ₂ and H ₂ O, the heavy metal is stably solidified in a sulfide form, the dissolution rate is less than 1% within the pH range of 3.0-8.5, and the problem of re-dissolution of the traditional hydroxide precipitate under an acidic condition is solved.

The environmental friendliness of the invention is further manifested in a low carbon footprint and recycling potential. Through sulfur element circulation (ROCSS ^-→ SO₄ ^2-→ S^2-) and flotation recovery of heavy metal sulfides (recovery rate is more than or equal to 95%), the double recycling of sulfur and metal resources is realized, and no additional carbon source is required to be added, so that no further pollution and no burden are caused to the environment.

In addition, the invention adopts a microbial inoculum carrier in a preferential scheme, and experiments show that after the biochar-nano ferroferric oxide is adopted as the microbial inoculum carrier, the tolerance of the composite microbial inoculum provided by the invention to extreme conditions is improved, and the porous structure and the slow-release Fe ²⁺ function of the biochar-nano ferroferric oxide optimize the mass transfer and electron transfer efficiency, so that the flora still maintains high activity under extreme conditions (pH 2.5-8.5 and heavy metal of less than or equal to 500 mg/L) and is suitable for the water quality variable characteristics of mine wastewater.

In summary, the method of the invention can synchronously remove pollutants of beneficiation reagent, intermediate degradation products and precipitated heavy metals by simply adding the special functional microbial inoculum of the invention into the wastewater to be treated at one time and culturing for several days under the condition of low temperature and energy consumption, the method solves the problem of complex pollution of organic mineral processing agents and heavy metals synchronously, has the advantages of low cost, no secondary pollution, green economy and the like, and provides a reference and candidate scheme with practical application value for constructing green, environment-friendly and efficient coupled biological metabolism treatment complex pollutants.

Drawings

FIG. 1 is a graph showing the degradation capacity of the composite microbial inoculum prepared in example 1 on potassium butylxanthate;

FIG. 2 is the solidifying ability of the composite microbial agent prepared in example 1 to heavy metals;

FIG. 3 is a degradation process of potassium butylxanthate and its intermediates for preparing a single flora and complex inoculant of example 2;

FIG. 4 is a comparison of degradation properties of the non-carrier-added and carrier-added composite microbial agents prepared in example 3;

FIG. 5 shows the effect of the composite microbial inoculum prepared in example 4 on the removal of potassium butylxanthate in a continuous flow reactor;

FIG. 6 shows the effect of the composite microbial inoculum prepared in example 4 on the removal of heavy metal lead and zinc in a continuous flow reactor;

figure 7 is an XRD pattern of the precipitate of the complex bacterial agent prepared in example 4 in a continuous flow reactor.

Detailed Description

Example 1 activation and construction of Complex microbial inoculants

Sulfur oxidizing bacteria (thiobacillus sp) strain, accession number DSM 612, commercially available from Beijing Bai Ou Bo Wei Biotechnology Co., ltd

Sulfate reducing bacteria (Desulfotomaculum _ profundi) strain, deposited under the number DSM 24093, purchased from Bekyo Bai Bo Wei Biotechnology Co., ltd

1. Activation of composite microbial agents

The sulfur oxidizing bacteria (thiobacillus sp) and sulfate reducing bacteria (Desulfotomaculum profundi) were removed from the frozen tube at-80 ℃ or liquid nitrogen and immediately placed on ice for thawing for 10 minutes. Wiping the surface of the freezing tube with 75% alcohol for sterilization, and transferring to an ultra-clean workbench.

50. Mu.L of SOB broth was pipetted with a sterile pipette and inoculated directly into 50 mL liquid medium （1.0 g/L NH₄Cl、0.5 g/L KH₂PO₄、0.2 g/L MgSO₄·7H₂O、5.0 g/L Na₂S₂O₃、15.0 g/L agar, pH 7.0), shake-cultured at 30℃for about 48 hours at 150 rpm to OD 600. Apprxeq.1.2. The cells were then washed 3 times (8000 rpm,10 min) with sterile PBS (phosphate buffer, pH 7.4) and finally resuspended to OD 600. Apprxeq.1.0 to give SOB suspension.

100. Mu.L of SRB broth was inoculated into 50 mL liquid medium (0.5 g/L KH ₂PO₄、1.0 g/L NH₄Cl、0.1 g/L CaCl₂·2H₂ O, 0.5 g/L yeast extract, 3.5 g/L sodium lactate, pH 7.2) using a sterile pipette, and incubated in an anaerobic serum bottle (N ₂:H₂:CO₂ =80:10:10) at 37℃for about 72 hours until OD600 ≡0.8, the cells were washed with anaerobic PBS and resuspended to OD600 ≡1.0 to give SRB suspension.

2. Construction and co-culture of composite microbial inoculum

Mixing SOB and SRB bacterial suspension obtained in the step 1 according to the volume ratio of 1:1, and inoculating to a basic inorganic salt culture medium (formula: 0.1 g/L NH ₄Cl、0.05 g/L CaCl₂、0.2 g/L MgSO₄, 100 mg/L butyl potassium xanthate, 50 mg/L cadmium chloride, pH 7.0) containing composite pollutants, wherein the inoculation amount is 1:50 (bacterial liquid: culture medium).

Placing the culture bottle in a constant temperature shaking table, setting a micro-aerobic condition (dissolved oxygen is 0.3-0.5 mg/L, and through intermittent micro-aeration regulation), and carrying out shaking culture at 30 ℃ and 120 rpm until the OD600 value reaches 0.6-1.0 to obtain the composite microbial inoculum.

3. Verifying degradation efficiency of composite microbial inoculum on xanthate of organic beneficiation reagent and removal effect of heavy metal cadmium

Adding butyl potassium xanthate (initial concentration is 200 mg/L) and Cd ²⁺ ions (initial concentration is 20 mg/L) into the constructed composite microbial inoculum reaction system. The flask was placed in a 30℃incubator with 120 rpm shaking, and dissolved oxygen DO was maintained at about 0.5 mg/L and pH 7.0-8.5.

Measuring the concentration change of butyl xanthate by ultraviolet spectroscopy;

the degradation capacity of the composite microbial inoculum to butyl potassium xanthate is evaluated, and the content of cadmium is measured by an atomic absorption spectrometry.

As shown in figure 1, the degradation rate of the composite microbial agent to butyl xanthate reaches 100%, and the removal rate to cadmium reaches 95%. And collecting solid precipitate generated in the reaction process, drying and then carrying out characterization X-ray diffraction patterns, wherein the result is shown in figure 2, and characteristic peaks of CdS appear in the object to be detected, which indicates that cadmium sulfide precipitate is generated in the reaction process.

Example 2 comparison of Single and Complex microbial Agents

The experiment researches the concentration change of the substrate and the intermediate metabolite in the degradation process of the xanthate

The test bacterial liquid is SOB bacterial suspension and SRB bacterial suspension prepared in the step 1 of the example 1.

A total of four treatments are:

(1) Blank group, namely a medium containing 200mg/L butyl xanthate basic inorganic salt;

(2) Inoculating SOB bacterial suspension to a medium containing 200mg/L butyl xanthate basic inorganic salt;

(3) SRB bacterial suspension, namely inoculating the SRB bacterial suspension to a medium containing 200mg/L butyl xanthate basic inorganic salt;

(4) Inoculating mixed bacterial agent (SOB+SRB group) to a medium containing 200mg/L butyl xanthate basic inorganic salt;

Three replicates were set for each treatment. According to the volume ratio of the bacterial liquid to the culture medium of 1:50, placing the bacterial liquid and the culture medium into 120rpm and 30 ℃ constant Wen Yaochuang for culture, sampling and measuring the concentration of butyl xanthate, total Organic Carbon (TOC), sulfate radical, sulfide and the like in the culture liquid every 24 hours.

As a result, as shown in fig. 3, in the blank (Control) group, no natural degradation process of potassium butylxanthate occurred, while the other experimental groups showed degradation efficiencies of (4) sob+srb group > (2) SOB group > (3) SRB group, which reached 99.6%,84.6%,63.2%, respectively, and it was seen that the composite microbial agent exhibited excellent degradation efficiency, see fig. 3 a, and that the composite microbial agent exhibited high degradation rate for complete removal of potassium butylxanthate. Meanwhile, the consumption rate of the intermediate product of the composite microbial agent is higher than that of a single microbial agent according to the concentration change of TOC and the concentration change of the intermediate product SO ₄ ^2-、S^2-, SO that the advantage of cross feeding of the composite microbial agent is reflected, namely, organic carbon sources such as SO ₄ ^2-, methanol/acetic acid and the like are generated by the potassium butylxanthate under the action of SOB, S ^2- is generated by SRB by using a metabolic small molecular organic matter reduction product SO ₄ ^2-, and the generated S ^2- is a source for forming sulfide precipitates, and a possible reaction equation is shown as follows.

4K(C₄H₉OCS₂) + 19O₂→ 2K₂SO₄+ 4H₂SO₄+ 4C₂H₅COOH + 4CO₂+ 6H₂O

2C₂H₅COOH + 3SO₄ ^2-+ 3H⁺→ 3H₂S + 6CO₂+ 3H₂O

S^2-+ Me⁺→ MeS

In the cross feeding process, the SOB metabolic products are continuously utilized by SRB to accelerate the SOB conversion process, so that the degradation of the composite microbial inoculum on butyl xanthate and TOC is obviously higher than that of a single flora.

Example 3 Effect of the use of the Carrier on the Mixed inoculant Properties

The experiment researches the performance of the composite microbial inoculum under the conditions of low pH and high heavy metal concentration, and the performance of the composite microbial inoculum is optimized after the carrier is added.

The microbial inoculum carrier is biochar-nano ferroferric oxide, and the manufacturer is Xiyinxi biological technology Co., ltd, and the product number is ZHQ+2022.3.

The experimental bacterial liquid is SOB bacterial suspension and SRB bacterial suspension prepared in the step 1 of the example 1.

The experimental method comprises dividing into 2 treatments, and setting three repetitions for each treatment

(1) Inoculating SOB bacterial suspension and SRB bacterial suspension into a culture medium containing 200mg/L butyl xanthate and 500 mg/L Cd ²⁺ basic inorganic salt, and mixing in equal volume;

(2) Adding a carrier group, namely inoculating an SOB bacterial suspension and an SRB bacterial suspension to a culture medium containing 200mg/L butyl xanthate and 500 mg/L Cd ²⁺ basic inorganic salt, mixing the suspension and the SRB bacterial suspension in equal volume, and adding biochar-nano ferroferric oxide and the mixed bacteria in a volume ratio of 1:1;

According to the volume ratio of the bacterial liquid to the culture medium of 1:50 and the pH value of 3.0, placing the bacterial liquid and the culture medium into a shaking table with the constant temperature of 120rpm and 30 ℃ for culture, sampling and measuring the concentration of butyl xanthate and Cd ²⁺ in the culture liquid every 24 hours.

As shown in FIG. 4, under the conditions that the pH is 3.0 and the concentration of Cd ²⁺ is 500 mg/L, the composite microbial inoculum has a certain inhibition effect, the removal rate of butyl xanthate and Cd ²⁺ is 49.8% and 4.54%, and when the biochar-nano ferroferric oxide is added, the high removal rate (99.82%) of the butyl xanthate and the high Cd ²⁺ concentration tolerance can be kept to achieve the removal rate of 64.40% even under extreme conditions.

The biochar-nano ferroferric oxide composite material is adopted as a carrier, so that the stress resistance of the flora is improved, the porous structure and the slow-release Fe & lt2+ & gt function of the composite material further optimize the mass transfer and electron transfer efficiency, and the flora still maintains high activity under extreme conditions (pH 2.5-8.5 and heavy metal less than or equal to 500 mg/L).

Example 4 treatment of xanthate-heavy Metal Combined contaminated wastewater

Experimental reagent:

The inflow water is artificial simulated xanthate-heavy metal composite polluted wastewater, namely xanthate (ethyl sodium salt) 200 mg/L, pb ²⁺100 mg/L、Zn²⁺100 mg/L、SO₄ 2-1200 mg/L, pH 8.8.8 and salinity (TDS) 2000 mg/L.

The equipment is an upflow packed bed reactor, the model is YRYYRY44556, the manufacturer is Shanghai bine to organic glass limited company, the volume is 5L, the diameter is 10 cm, and the height is 63.7 cm.

The preparation of the microbial inoculum comprises the steps of mixing SOB and SRB bacterial suspension obtained in the step 1 of the example 1 according to the volume ratio of 1:2, and inoculating the mixture to a basic inorganic salt culture medium containing composite pollutants (formula: 0.1 g/L NH ₄Cl、0.05 g/L CaCl₂、0.2g/L MgSO₄, 100 mg/L butyl potassium xanthate, 50 mg/L cadmium chloride, pH 7.0), wherein the inoculum size is 1:50 (bacterial liquid: culture medium). Placing the culture bottle in a constant temperature shaking table, setting a micro-aerobic condition (dissolved oxygen is 0.3-0.5 mg/L, and through intermittent micro-aeration regulation), and carrying out shake culture at 30 ℃ and 120 rpm until D600=1.0 to obtain the liquid composite microbial inoculum.

The processing flow is as follows:

And (3) adopting an up-flow packed bed reactor to treat and verify the simulated mine wastewater. The reactor is filled with the biochar-nano ferroferric oxide composite material, and the filling rate (the ratio of the biochar-nano ferroferric oxide composite material to the volume of the reactor) is 40%;

in the starting stage of the reactor, firstly adding 500 mL pre-activated liquid composite microbial inoculum, and standing for 2 hours to enable the microbial community to be adsorbed on the surface of the microsphere;

The Hydraulic Retention Time (HRT) is controlled to be 8 hours during operation, the temperature is 35+/-1 ℃, the oxidation-reduction potential (ORP) is dynamically regulated to-150+/-10 mV through an online sensor,

Dissolved Oxygen (DO) is maintained at 0.5-1.0 mg/L in the aerobic zone, and the oxygen concentration in the anaerobic zone is lower than 0.2 mg/L.

The biochar-nano ferroferric oxide composite material is supplemented every day to ensure the filling rate to maintain the activity of the flora, and continuous water inlet and outlet are realized through a peristaltic pump (the flow rate is 6.25L/h).

In the treatment process, water samples are continuously monitored for 30 days and collected every day to determine the concentration of butyl xanthate, heavy metals Pb and Zn. As shown in FIG. 4, the degradation rate of butyl xanthate (ethyl sodium salt) was maintained at 98.9.+ -. 1.0%. As shown in FIG. 5, the removal rates of Pb and Zn heavy metals are 94.7% and 89.2% respectively. And XRD characterization of the resulting solid (fig. 6), both found characteristic peaks for PbS and ZnS.

Therefore, the composite microbial inoculant prepared by the method has the application potential of synchronously removing the organic beneficiation reagent and fixing heavy metals.

Claims

1. A cross-feeding composite bacterial agent for simultaneously removing mineral processing agents and heavy metal contamination, characterized in that: a mixed bacterial liquid of a sulfur-oxidizing bacteria ( Thiobacillus sp) suspension and a sulfate-reducing bacteria ( Desulfotomaculum profundi) suspension is inoculated into a liquid culture medium, and cultured at a constant temperature of 30°C and microaerobic conditions with shaking at 120 rpm until the OD600 value reaches 0.6-1.0 to obtain the cross-feeding composite bacterial agent;

The liquid culture medium is a basic inorganic salt culture medium containing simulated composite pollutants, with the following formula: 0.1 g/L NH ₄ Cl, 0.05 g/L CaCl ₂ , 0.2 g/L MgSO ₄ , 100 mg/L xanthate, 50 mg/L cadmium chloride, and a pH of 7.0;

During inoculation, the volume ratio of the mixed bacterial solution to the liquid culture medium is 1:50, and the concentration ratio of the sulfur oxidizing bacteria to the sulfate reducing bacteria in the mixed bacterial solution is 1:3 to 3:1;

The cross-feeding refers to the following process in the composite bacterial agent: sulfur-oxidizing bacteria oxidize the sulfur groups in xanthate to SO ₄ ^2- and provide the electron acceptor required by sulfate-reducing bacteria; at the same time, sulfate-reducing bacteria use the intermediate products degraded by sulfur-oxidizing bacteria as a carbon source to reduce SO ₄ ^2- to S ^2- . The produced S ^2- forms a stable sulfide precipitate with heavy metals.

2. The cross-feeding composite bacterial agent according to claim 1, wherein the concentration ratio of the sulfur-oxidizing bacteria suspension to the sulfate-reducing bacteria suspension in the mixed bacterial liquid is 1:1 to 1:2; the microaerobic condition refers to maintaining the dissolved oxygen at 0.3 to 0.5 mg/L through intermittent micro-aeration regulation; and the xanthate refers to potassium butyl xanthate.

3. The cross-feeding composite bacterial agent according to claim 1 or 2, characterized in that the sulfur-oxidizing bacteria are species with a deposit number of DSM 612, and the sulfate-reducing bacteria are species with a deposit number of DSM 24093.

4. A method for simultaneously removing contamination from non-ferrous metal mine dressing agents and heavy metals, comprising the following steps:

Feeding: Adding the cross-feeding composite bacterial agent according to any one of claims 1 to 3 to the wastewater to be treated containing non-ferrous metal mineral processing reagents and heavy metal pollution to carry out reaction, with the added volume being 5-15% of the volume of the reaction container;

Reaction conditions: At a temperature of 10°C to 30°C, control the water inlet and outlet of the reaction vessel to ensure a hydraulic retention time of 2 to 10 hours for the wastewater to be treated. No carbon source needs to be added during this period.

The mineral processing agent is xanthate, and the heavy metal is at least one of copper, cadmium, lead and zinc.

5. The method according to claim 4, characterized in that the pH value of the wastewater to be treated is 7.0 to 8.5, the xanthate concentration is 1.0 to 1000 mg/L, and the heavy metal element concentration is 0.1 to 100.0 mg/L.

6. The method according to claim 4, wherein the reaction conditions further include controlling the concentration of dissolved oxygen to ≤0.5 mg/L.

7. The method according to claim 4, wherein the reaction vessel is an upflow packed bed reactor; a peristaltic pump is used to continuously supply and discharge water;

The reaction vessel is filled with a bacterial agent carrier with a filling rate of 30~45%;

After adding the cross-feeding composite microbial agent, the mixture is allowed to stand for 1-2 hours to allow the microbial cells to be adsorbed to the microbial agent carrier.

8. The method according to claim 7, wherein the bacterial agent carrier is biochar-nano ferroferric oxide.

9. The method according to claim 7, wherein during operation of the reaction vessel, the hydraulic retention time is controlled to be 8 hours, the temperature is 35±1°C, the redox potential is -150±10 mV, the dissolved oxygen is maintained at 0.5-1.0 mg/L in the aerobic zone and below 0.2 mg/L in the anaerobic zone, and the flow rate is controlled by a peristaltic pump at 6.25 L/h to achieve continuous water inflow and outflow.

10. The method according to any one of claims 4 to 9, further comprising solid-liquid separation of the treated wastewater, wherein the supernatant is clean water free of xanthate-heavy metal composite pollution; the solid is sulfide precipitate, and heavy metal resources are recovered by magnetic separation.